/**
 * Given a linked list, remove the nth node from the end of list and return its head.
 * For example,
 * Given linked list: 1->2->3->4->5, and n = 2.
 * After removing the second node from the end, the linked list becomes 1->2->3->5.
 * <p>
 * Note:
 * Given n will always be valid.
 * Try to do this in one pass.
 * <p>
 * Created by drfish on 16/04/2017.
 */

public class _019RemoveNthNodeFromEndOfList {
    public ListNode removeNthFromEnd(ListNode head, int n) {
        ListNode dummy = new ListNode(-1);
        dummy.next = head;
        ListNode fast = dummy;
        ListNode slow = dummy;
        for (int i = 0; i < n; i++)
            fast = fast.next;
        while (fast.next != null) {
            fast = fast.next;
            slow = slow.next;
        }
        slow.next = slow.next.next;
        return dummy.next;
    }
}